1. Field of the Invention
This invention relates generally to the field of otological diagnostic procedures. More particularly, the invention relates to a method for aligning derived-band auditory brainstem responses (ABRs) to acoustic stimuli.
2. Background
U.S. Pat. Nos. 6,080,112 and 6,264,616, the disclosures of which are incorporated herein by reference, disclose a diagnostic technique for detecting small (≦1 cm) intracanalicular tumors. The procedure first records a patient's auditory brainstem response (ABR) to each of a plurality of auditory stimuli. The stimuli comprise 60 dB nHL clicks using high pass noise masking procedures to isolate the cochlear response within specific frequency bands. These derived band ABRs are temporally shifted to align the wave V peak amplitudes. The time-shifted responses are then summed to create a “stacked ABR”. The stacked wave V ABR amplitude is compared to a threshold value. The stacked wave V ABR amplitudes for patients having small (less than or equal to 1 cm.) intracanalicular tumors are measurably lower than those for otherwise similar individuals without tumors.
In the above-referenced patents, the derived-band response waveforms are aligned according to the peak latencies of wave V in each derived-band response. However, the alignment process depends on operator judgment and it is often difficult to determine where the peak of wave V occurs for some of the derived-band responses. This invention provides a different way of aligning the responses before the summation process and avoids having the operator make decisions about where the peak latency of wave V occurs for the derived bands.